During processing, photographic material is usually immersed in a number of processing solutions in a predetermined sequence. This may be effected either by placing the photographic material in a single tank and sequentially filling the tank with the various processing solutions or by filling a number of tanks with the different processing solutions and conveying the photographic material from one tank to the next. Examples of the processing solutions include developing solution, fixing solution, and washing solution.
Regardless of which processing method is adopted it is always necessary to fill one or more tanks in a photographic processing apparatus with the appropriate solution before the material is processed and then to empty the or each tank either so that it can be refilled with a different solution or to prevent aerial degradation if the solution is not going to be used for some time.
The processing solutions comprise chemicals which can, in some cases, be hazardous to handle. It is therefore desirable to eliminate or reduce to a minimum the handling of the solutions by persons operating the photographic processing apparatus.